1. Field of the Invention
The present invention relates generally to a recording and/or reproducing apparatus and is directed more particularly to a magnetic recording and/or reproducing apparatus having at least a pair of rotary magnetic transducing heads.
2. Description of the Prior Art
In a so-called helical scan type video tape recorder (VTR), there has been proposed such an apparatus in which the azimuth angles of recorded signals are made different with each other between adjacent tracks to omit a guard band and magnetic transducing heads each having the head width larger than the track width are used to perform the recording and/or reproducing.
In connection with the above apparatus, it is proposed that the wrapping angle of a magnetic tape around a rotary drum is selected larger than the angular distance or rate of the heads to provide an overlap interval in which plural heads contact with the tape at the same time and an audio signal, which is, for example, a pulse-code-modulated (PCM) signal and is time-base-compressed, is recorded on the tape during the above overlap interval.
FIG. 1 is a tape format showing a recorded track pattern on a magnetic tape by the manner mentioned just above. In FIG. 1, the track is sequentially formed on the tape from the left side of the sheet of the drawing and each track is recorded from the lower side of the tape to its upper side. In FIG. 1, on the portion with hatches recorded is a PCM audio signal and on the portion with no hatch recorded is a video signal, respectively.
Upon the recording mode, the portion or region of each track shown by the solid and broken line in FIG. 1 is magnetized by the recording signal and when a next track is recorded, a part of the former track is erased by the recording of a next signal so that the regions shown by the solid lines are made as recorded tracks, respectively.
With the above apparatus, it is possible that only the PCM audio signal, by way of example, is re-recorded on the tape which is once recorded so as to perform a so-called after recording. In such a case, for example, the rotary phase of the rotary heads is detected by a pulse generator and so on as well as the above-mentioned overlap portion is discriminated or identified and then a PCM audio signal is supplied to the heads and recorded thereby during the interval in which the heads contact with the overlap portion of the tape. Consequently, by this recording the PCM audio signal which was already recorded is erased and the new PCM audio signal is recorded.
In case of this recording, when the PCM audio signals on, for example, tracks a.sub.7 to a.sub.12 in FIG. 1 are re-recorded to be tracks b.sub.7 to b.sub.12 as shown in FIG. 2, a part of the next track a.sub.13 is erased by the track b.sub.12 recorded last and hence the width of the track a.sub.13 becomes very narrow. In other words, upon the normal recording a part of the track b.sub.12 which is to be erased by the recording of the next track a.sub.13 is not erased and hence the width of the track a.sub.13 becomes narrower by that amount.
Further, there may be such a case that if the relative position of the head to the first track b.sub.7 on which the re-recording is carried out is not correct, the former track a.sub.6 is erased too much by the recording of the track b.sub.7 as compared with the case of the correct position and hence the width of the track a.sub.6 becomes narrow.
As the track width of the PCM audio signal portion becomes narrower as set forth above, a reproduced signal therefrom is deteriorated, an error is caused upon the PCM demodulation and accordingly noise is generated.